The goal of this proposal is the creation of the Ascidian Stock Center (ASC). Ascidians are an emerging model system for the study of embryology, gene regulatory networks, chordate evolution and comparative physiology. Ascidians have great potential as a model system, but they present unique experimental challenges. One of the limitations of ascidian model is the dependence of most of the ascidian community on wild-caught animals. While several species are studied, ascidians of the Ciona genus (C. intestinalis and C. savignyi) are becoming the most widely used, largely due to their wide spread distribution in the wild. The dependence of most laboratories on wild-caught animals means that supplies are unreliable, and sometimes unattainable, and that the types of experiments that can be done are limited. We have established an ascidian culturing facility at the marine laboratory of the University of California at Santa Barbara (UCSB). The Specific Aims of this application propose an expansion of the UCSB facility to accommodate a stock center that will service the growing ascidian community. The purpose of the stock center are two-fold: 1) provide a supplemental source of Ciona adults for research laboratories;and 2) generate and distribute a set of stable transgenic animals that carry tissue-specific enhancers that drive GFP.